CHAPTER 7FLASH IN STEREOOST MODERN STEREO CAMERAS are equipped with internal
M synchronization for flash, but too many stereographers
neglect this technique and so lose a great deal of pleasure which
would otherwise be theirs.
For some reason the idea persists that flash is restricted to mak-
ing photographs at night, and a great number of stereographers
still lower or extinguish the room lights when preparing to make
a flash exposure. This is all wrong. Flash is intended for use
under normal conditions of artificial lighting or in full daylight.
That is the reason for the synchronized flash instead of the “free”
or “wild” type.
Flash is a technique whereby the photographer can produce a
light of sufficient intensity for making the exposure in such a short
time that the great intensity is not painful and has no significant
heating effect. To produce this light at just the right instant,
synchronization is used.
For older types of shutters, there are various types of mechani-
cal synchronizers which ignite the bulb and open the shutter at
the same instant. The whole action may be mechanical, or the
motion of the shutter may close a contact to ignite the bulb, or
pressure upon a button may ignite the bulb and activate a sole-
noid which operates the shutter. But in modern cameras, the con-
tacts are usually built into the shutter itself so all that is necessary
is to provide a socket for the bulb with associated reflector and
the battery case.
Synchronization may be either for a 5-millisecond delay or for
a no-millisecond delay type of bulb.
The F (SF or SM) bulb has a duration of about i/ioo second
so it may be used with slow shutters in inexpensive cameras for
relatively high speed shots. The M (5 or 25) bulbs are wire-filled
and have a broader peak, so they are best used with a shutter
which can be set for the desired speed. Synchronization set for
one of these types will not necessarily serve for the other, so be
sure which type your camera or gun is set for. The midget M bulb
(5 or 25) is wire-filled, the F bulb (SF or SM) has no filling. The
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